Disproportionation of olefins

ABSTRACT

A catalyst for olefin disproportionation comprises a molybdenum or tungsten salt and a Group IVb organometallic compound. A preferred system is tungsten hexachloride and tetra-n-butyl tin.

. I I Umted States Patent 1191 [111 3,723,563

Bradshaw Mar. 27, 1973 [54] DISPROPORTIONATION OF OLEFINS [58] Field of Search ..260/683 D [75] Inventor: Christopher I Patrick Cadman Bradshaw, Sunbury-on-Thames, En- [56] References C'ted gland UNITED STATES PATENTS [73] Assigme: P", British Petmleu'" 3,026,269 3/1962 Gresham etal. ..252/429 Lmdon, England 3,166,547 l/1965 Loeb ..252/429 [22] Filed: Jul 12,1971 3,232,920 2/1966 Naylor ..252 429 [211' Appl- 162,021 Primary ExaminerDelbert E. Gantz 7 Assistant ExaminerC. E. Spresser l D Related U S App canon am Attorney-Morgan, Flnnegan, Durham & Pm [63] Continuation of Ser. No. 799,497, Feb. 14, 1969,

abandoned- 57 ABSTRACT [30] Foreign Application Priority Data A catalyst for olefin disproportionation comprises a molybdenum or tungsten salt and a Group IVb or- Mar. 5, 1968 Great Bntam ..10,629/68 ganomvetallic compound A preferred system is tung sten hexachloride and tetra-n-bu'tyl tin. [52] US. Cl. ..260/683 D Y [51] Int. Cl ..C07c 3/62 6 Claims, No Drawings DISPROPORTIONATION OF OLEFINS A disproportionation reaction is one in which an olefin is converted to products having higher and lower carbon numbers than the olefin starting material; and a disproportionation catalyst is a catalyst which is capable of effecting such a reaction. Heterogeneous disproportionation catalysts are known, for example, a mixcoreaction of acyclic olefins which process comprises contacting two dissimilar acyclic olefins of the formula RR C CR R and R R C CR R with the defined disproportionation catalyst system under conditions of temperature and pressure which effect coreaction of the feed, the R 'substituents representing hydrogen atoms, alkyl or aryl groups, with the proviso that not more than two of the groupings RR,C R R C I R R,C or R,R-,C are the same.

Acyclic olefins suitable as feeds include C alkenes, preferably C straight chain alkenes. The alkenes may be alpha, beta or gamma etc., alkenes. Suitable alkenes include propylene, butene-l, butene- 2, pentene-l, pentane-Z, hexene-l, hexene-Z, hexene- Excluding benzene ture of molybdenum oxide and alumina, preferably 3, heptene-l, heptene-2, heptene-3, octene-l, octenecontaining cobalt oxides, and optionally containing '2, etc. Branched chain C alkenes are also suitable minor amounts of alkali metal or alkaline earth metals; feeds. molybdenum, tungsten or rhenium carbonyls sup- It is preferred to remove all traces of noxious impuriported on alumina, silica or silica-alumina; tungsten ties from the feed, e.g., by treating the pentene-2 feed oxide supported on alumina and rhenium heptoxide on with tungsten hexachloride which is subsequently I alumina. removed by percolation through a silica column.

In South African Pat. No. 67/1913 a homogeneous The reaction temperature may be from 100C to catalyst system is described comprising three com- +300C,prcferab1y from -20C to +50C. ponents: (A) an organometallic compound of Groups The reaction pressure may be from 10 mm of mercu- Ia, Ila, IIb, or [11a of the Periodic Table (B) a salt of ry"t0 2,000 psig, preferably that pressure which will molybdenum or tungsten and (C) a defined organic maintain the reaction in the liquid phase e.g. 0 200 compound containing oxygen or sulphur e.g., ethyl alp gcohol. The reaction may be performed in the gaseous or It is an object of the present invention to provide new q P a Prefembly in the liquid P and y be and useful homogeneous disproportionation catalysts. operated continuously batch-wise v has now been discovered homogeneous dis- Suitable ratios of Olefin t0 tungsten 0r molybproportionation catalyst systems can be prepared condenum Salt are from 10611 to 211 Preferably 10411 to taining an organometallic compound of Group Nb of 10211? i r the periodic 1 Suitable weight ratios of tungsten or molybdenum Thus according to the presentinvention there is prov to Group Ivb metal compound are from 511 to videdv a homogeneous disproportionation catalyst 00111 P a y fmmlil to system comprising (i) a salt of-molybdenum or tungsten The catalyst system may be P p y i g the and (ii) organometallic o n ametal of 40 components (i) and (ii) referred to above in the inert Group IV!) of the Periodic Table according to Mendebenzene, cyclohexan-e p The leaf dilution is not critical. g

The preferred salts of tungsten and molybdenum are T d" is illustrated but not limited by the tungsten hexachloride and molybdenum pentachloride. lowmg Examples- Tungsten hexachloride is the more preferred.

The organometallic compound of the Group IVb EXAMPLEI metal (e.g., Ge, Sn or Pb) should have at least one Solutions of 0.025 M of WCI and 0.2 M of Sn(nmetal to carbon bond. The preferred compounds are C 11 were made up in benzene which had been those of tin, more preferably: tetra n butyltin. freshly distilled over potassium metal. Aliquots of these The invention also comprises a disproportionation l ti n were dded to 1 m le of dr pentene-Z process which process comprises'contacting an acyclic diluted with 15 ml of dry benzene. The solutions were olefin of formula RR,C CR R wherein the R subthoroughly mixed and allowed to stand for 24 h at amstituents represent hydrogen atoms or alkyl or aryl biem tem erature, To ea h as then dded 1 l f groups with the above defined homogeneous dispromethanol to terminate the reaction. 'The reaction portionation catalyst system under conditions of temproducts were then analyzed. All operations were carperature and pressure which effect disproportionation ried out in a dry N atmosphere. The results of a'series of the feed. of experiments, in which the proportion of Sn(nC l'I The invention further comprises a process for the was varied, are tabulated below:

7 ml of ml of 0.2 Molar ratio *lroducts percent wt .0-025M 0.2M of Conversion wclii SN(nC..H,.)1 Pentene-Z/ percent wt Butene-2 Pentene2 Hexene-3 added added W/Sn EXAMPLE2 In this example the benzene was distilled over potassium metal and percolated through a silica column which had been activated at 580C. The pentene-2 feed was purified by treating with silica in the same manner.

0.01 Millimole of WCl. (1.0 ml 0.01 M WCI in benzene) followed by 0.1 millimole of Sn(n-Bu) [1.0 ml 0.1 M Sn(n-Bu) in benzene] were added to 5.5 ml

of pentened2 in 6.0 ml of benzene in an atmosphere of EXAMPLE 3 Benzene and pentene-Z were purified as in Example 1 except that pentene-2 was further purified by adding WCl (1 mole/15,000 mole of G5) which was subsequently removed by percolation through a silica column.

0.005 Millimole of WCl (0.5 ml of 0.01 M WC] in benzene) followed by 0.05 millimole of Sn(n-Bu) [0.5 ml of 0.1 M Sn(n-Bu) in benzene] were added to 5.5 ml of pentene-2 and 6.0 ml of benzene in an atmosphere of dry nitrogen such that molar ratios of CflzWcSn were 10,000:] :10. The mixture was agitated occasionally and the reaction terminated with isopropanol after 30 minutes when analysis showed a conversion to C and C5 of 45 per cent. Using an identical catalyst at a feed to tungsten ratio of 15,000:1 a conversion of 18.9 per cent was observed after 30 minutes.

EXAMPLE 4 Benzene and pentene-Z were purified as in Example 2. A catalyst identical to that in Example 1 except that Sn(n-Bu was replaced by SnMe was used.

0.05 millimole (5.0 ml of 0.01 M WCl in benzene) followed by 0.5 millimole SnMe [5.0 ml of 0.1 M SnMe in benzene] were added to 5.5 ml of pentene-2 in an atmosphere of dry nitrogen such that the molar ratios of Cg'zWzSn were 1,000:1:10. The mixture was agitated occasionally and the reaction terminated by the addition of isopropanol after 30 minutes when analysis showed conversion to C and C of 47.7 per cent.

EXAMPLE 5 In this example a catalyst was prepared from PbMe, and .WCI Benzene and pentene-Z were purified as in Example 1.

0.0125 millimole WCl (0.125 ml 0.01 M WCl,.in benzene) followed by 0.125 millimole PbMe [1.25 ml 0.1 M PbMe in benzene] were added to 5.5 ml of pentene-2 in an atmosphere of dry nitrogen such that the molar ratios c.-=w;Pb were 4,000zlzl0. The mixture was agitated occasionally;,after 30 minutes the conversion to Cf and C was 8.0 percent; after a 64 hour contact time the-conversion to C and C54 had increased to 20.0 per cent.

' EXAMPLE 6 Benzene and a mixture of pentene-2 and pentene-l were purified as in Example 2.

0.02 millimoles of WCl (20ml of 0.01 M WCI followed by 0.2 millimole Sn(n-Bu) [2.0 ml Sn(n-Bu) 0.1

M] were added to 1.1 ml per cent, pentene-2 86.3 per cent, in an atmosphere of dry nitrogen suchthat the molar ratios of C :W:Sn were 500:1:10. The mixture was agitated occasionally and the reaction terminated by addition of isopropanol after 30 minutes when analysis showed a conversion to C Cf, C C-f'Of 25 per cent. Using an identical catalyst and a feed to tungsten ratio of 1,000z1 the conversion to C C C C C and C- 'is 14.5 per cent.

The following reactions took place:

The detailed results for these two experiments were as given below:

C ':W:Sn Products wt molar ratio C C; C, C; 500:1:10 1.3 7.9 75.0 12.5 3.3 1000:1110 0.5 5.5 85.5 6.8 1.8

Examples 2 and 3 illustrate that improved feed purification increases the activity of the catalyst. Example 4 shows that alternative Sn alkyls may be used. Example 5 shows that Pb alkyls are active. Example 6 demonstrates that the coreaction of mixed olefins (including a-olefms is effected by these catalysts.

What is claimed is:

1. A process for the coreaction of acyclic olefins which process comprises contacting two dissimilar acyclic olefms comprising C, to C alkenes of formula RR,C= CR,R and R R C==CR,R with adisproportionation catalyst system comprising (1 salt of molybdenum or tungsten and (2) an organometallic compound of a metal of Group [Vb of the Periodic Table according to Mendeleef in an inert solvent selected from benzene, cyclohexane, or n-heptane under conditions of temperature in the range of C to +300C and pressure which affect coreaction of the feed, and R substituents representing hydrogen atoms or alkyl groups, with the proviso that not more than 2 of the groupings RR,C=, R R,C=, R R C= or R R-,C= are the same.

2. A process according to claim 1 wherein the feedstock comprises C straight chain alkenes.

3. A process according to claim 1 wherein the salt of molybdenum or tungsten is tungsten hexachloride or molybdenum pentachloride.

4. Aprocess according to claim 1 wherein the organometallic compound is tin.

5. A process according to claim 4 wherein the compound of tin is tetra-n-butyl tin.

6. A process according to claim 1 wherein the reaction is effected. at a temperature in the range 20C to +50C.

* B i t i of a mixture of pentene-l 13.7 

2. A process according to claim 1 wherein the feedstock comprises C3 8 straight chain alkenes.
 3. A process according to claim 1 wherein the salt of molybdenum or tungsten is tungsten hexachloride or molybdenum pentachloride.
 4. A process according to claim 1 wherein the organometallic compound is tin.
 5. A process according to claim 4 wherein the compound of tin is tetra-n-butyl tin.
 6. A process according to claim 1 wherein the reaction is effected at a temperature in the range -20*C to +50*C. 